• Energy Research

This study assessed the extremes of wave conditions for past (1979–2005) and future (2026–2045 and 2081–2100) time slices in the Gulf of Guinea (GoG). The ensemble produced from eight General Circulation Models under different Representative Concentration Pathway (RCP) emission scenarios (RCP4.5 and RCP8.5) was subjected to linear regression analysis and Mann–Kendal test for their trends and significance, respectively. Results showed an increase in the extreme of significant wave height (Hs) and mean wave period (Tm) between 1979–2005, 2026–2045, and 2081–2100 with few exceptions. The average values of annual and seasonal Hs and Tm range from 1.26–1.62 m and 10.37 s–10.86 s, respectively, for 1979–2005. These Hs values are projected to increase by 0.1 m (0.05 m) to 1.72 m (1.67 m) and the Tm will increase by 0.29 s (0.24 s) to 11.15 s (11.10 s) by the end of the century (mid-century) time slices, respectively. The mean wave direction (Dm) (201.89°–206.27°) showed an anticlockwise shift (−29.2 × 10−3 degrees per year) for 1979–2005 which is projected to become more southwesterly with an increase up to 2.2° (0.5°) by end (mid) century in 2100 (2045), respectively. Future work will be on the impacts of changing wave on longshore sediment transport along the GoG.

AbstractRegular and long-term monitoring of coastal areas is a prerequisite to avoiding or mitigating the impacts of climate and human-driven hazards. In Africa, where populations and infrastructures are particularly exposed to risk, there is an urgent need to establish coastal monitoring, as observations are generally scarce. Measurement campaigns and very high-resolution satellite imagery are costly, while freely available satellite observations have temporal and spatial resolutions that are not suited to capture the event scale. To address the gap, a network of low-cost, multi-variable, shore-based video camera systems has been installed along the African coasts. Here, we present this network and its principle of sharing data, methods, and results obtained, building toward the implementation of a common integrated coastal management policy between countries. Further, we list new contributions to the understanding of still poorly documented African beaches’ evolution, waves, and sea level impacts. This network is a solid platform for the development of inter-disciplinary observations for resources and ecology (such as fisheries, and sargassum landing), erosion and flooding, early warning systems during extreme events, and science-based coastal infrastructure management for sustainable future coasts.

In the context of global warming marked by rising sea levels and extreme meteorological events, it is imperative to gain a comprehensive understanding of coastal vulnerability to flooding, as this knowledge is essential for safeguarding both communities and ecosystems. Using high-resolution satellite-derived digital elevation models and global ocean reanalysis, the degree to which a part of Nigeria's Mahin mud coast in the Gulf of Guinea of the North Atlantic Ocean is vulnerable to coastal flooding is assessed. The results show that the study area is at risk of being affected by both present and future extreme coastal flooding events, which poses a significant threat to coastal integrity and stability. It faces potential deterioration in coastal flooding due to future SLR consequences. Mean ECWLs are projected to increase from 1.6 m in 1993-2015 (present) to 2.1 and 2.2 m by 2050, with further acceleration to 2.4 and 2.85 m by 2100, under SSP2-4.5 and SSP5-8.5, respectively. This increases the risk of extreme coastal water levels, with land submerged by 125 km2 and 170 km2 under SSP2-4.5 and SSP5-8.5 climate scenarios by 2100. The study area's exposure to ECWF increased from 2181 to 2312 buildings in 2050 and 3003 in 2100 under SSP2-4.5 and SSP5-8.5, with potential exposure increasing from 24,856 to 128,083 people in 2100 under SSP5-8.5, highlighting the area's high vulnerability to sea level rise. It is therefore crucial to develop a sustainable strategy to protect the mud coast from degradation and promote sustainable development, thereby mitigating the present and future coastal retrogradation.